Valve mechanism



Patented Nov. 3, 1925.

UNITED STATES PATENT OFFICE.`

EDGAR D. DIGKINSON, OF BEVERLY,`AND REGINALD G. STANDERWICK, 0F MARBLE- HEAD, MASSACHUSETTS, ASSIGNORS TO GENERAL ELECTRIC COMPANY, A GOR PORATION OF NEW YORK.

'VALVE MECHANISM.

Application led February 13, 1924. Serial No. 692,601.

To all whom t may concer/a.'

Be it known that we, EDGAR l). DICKIN- son and REGTNALD Gr. STANDnnwion, citizens of the United States, residing, respec tively, at Beverly, in the county of Essex, State of Massachusetts, and at Marblehead, in the county of Essex, State of Massachusetts, have invented certain vnew and useful Improvements in Valve Mechanisms, of which the following is a specification.

The present invention relates to valve mechanisms such as are used to control the admission of elastic fluid to' turbines for eX- ample, and has for its object to provide an improved mechanism for actuating such valves which is simple in structure, positive in operation, and can be manufactured at a low cost.

For a consideration of what we believe to be novel and our invention, attention is directed to the accompanying description and the claims appendedthereto.

In the drawing, Fig. 1 is a side elevation of a part of a turbine equipped with a valve mechanism embodying our invention, cer tain parts being broken away and others being shown in section; Fig. 2 is a detail sectional view ofthe valve mechanism showing it in open4 position: Fig. 3 is a detail side view of certain parts, and Fig. 4 is a diagram.

Referring to the drawing, 1 'indicates anelastic fluid turbine of suitable structure provided with a chest 2 to which elastic fluid is supplied yby a suitable`pipe` (not shown) and from which elastic fluid flows through one or more ports 3 to the nozzles 4l which direct the elastic fluid to the buckets on the bucket wheel` 5. Only the high pressure end of the turbine is shown in the drawing. It will be understood that the ar rangement shown is to be taken as typical of any suitable turbine structure. The flow of elastic fiuid through eachlport 3 is controlled by a valve 6, the stem 7 of which extends through a stuiiing box 8 to the outside of the turbine casing. In general, in a turbine of the type illustrated, there are several valves 6 which are opened and closed one after another to control the admission of elastic iiuid to the turbine. Each valve 1s opened by a cam.9 on a cam shaft 10 journaled in bearings in suitable brackets, one of which is shown at 11. Cam shaft 10 is turned by a gear wheel 12 which meshes with a'rack 13 on the upper end of a rod 14. The lower end of rod 14 is connectedk to the piston of the hydraulic 'motor 15.V The hydraulic motoris shown only partially and in outline. It willbe understood that it may be of any desired or known type, and may include the usual pilot valve which is moved by the turbine speed governor.

Our present invention relates particularly to the connection between valve stem 7 and cam 9 through which the cam operates the valve. Connected to the outer end of stem 7 is a curved head 16.which encircles cam 9 and carries a roller 17 withV which the i peripheral surface of the cam engages, the

roller being iiXed on a pin 18 journaled in suitable bearings in head 16.v Head 16 may be fastened to stem 7 in any suitable manner, it being shown in the present instance as being provided with a socket 19into which the end of the stem fits and with a split sleeve 2O which is tightened around the steinby a bolt 21 which passes through ears 22 on the sleeve. Garn 9 has a lifting surface 23 and a holding surface 24, the center of curvature of the latter being the center of shaft 10. With thisarrangement, i

whenV shaft 10 turnsin the direction indicated by the arrow in Fig. 4, valve 6 is first raised by the lifting surface 23, and after being fully opened is held `open by surface 24. Surface 24 has a considerable circumferential extent so that it will hold the valve open while shaft 10 continues to turn to open additional valves.

Referring particularly to Fig. 4, and` con.- sidering it in connection with Fig. 1,` it will be clear that, if roller 17were in line with stem 7 then when cani 9 turns in the direction indicated bythe arrow A to open valve 6 it would place lside thrus-J on stem =7 in l cracked from its seat. .once off its seat, the pressure on opposite the direction indicated by the arrow B. To y initially lift valve 6 off its seat requires considerableforce because of the elastic iiuid pressure in chest 2 so that at this time the Side thrust may be large. To overcome this, we place the center of roller 17 to one side of the center line of stem 7 and then place the point of contact between surface 23 of cam 9 and roller 17 at a point intermediate between the center line vof stem 7 and a line drawn parallel to it through the center of roller 17. This is plainly shown in Fig. l wherein C indicates the center line of stem 7, D indicates the center line of roller 17 and E indicates the point of contact. lVith this arrangement the' lifting. action of cam 9 produces on stem 7 a force having a component in the direction olf the arrow Bi and also a componentin the direction of the narrow' F. The component in the direction of thev arrow F may" bey termed a counteract` ing component and may be given any desired value by varying4 the position of the point of contact E. Preferably we so lo- Vcate point of Contact E that the side thrust represented bythe arrow F just counteracts the side thrust in the direction of the arrow B at the* time of maximum lifting force of the: cam, i. e., when the valve is being After the valve is sidesof it equalizcs rapidly as the valve continues to opensc that the force required to continue. opening movement of the valve decreasesV very rapidly and substantially. The side thrusts are exactly equalized only for the one value of the lifting-force. At other values there willV be a resultant side thrust and@ to take: care of this we provide on the side;` walls of head 16 flatfsurfa'ces 25 which roll? along the hubs"26 of cam 9..V rThis serves to prevent bending; of the stem by the resulta-nt side thrust, such sidethrust being talenvby, the brackets 1.1.

The valveis biased toward closed position by a spring 27 which 1s attached at one end to the head1 of the turbine and at the other end to a short arm 28 projecting from head 16. Spring 27 holds roller 17 in engagement with the surface of cam 9 and causes the valve to move: toward closed position.

- Between the side walls of head 16' and oni the side'of canr 9 opposite tothat at which roller 17 is,` located there is pivoted a roller 29.

During normal operation therel is ya slight vclearance between roller 29 and'the surfaceoff cani 9. In case the valve sticks open, spring 27 proving insulicie-nt to start it toward closed position,cam 9 in moving in a direction to e'ect. closing-of valve 6 will strike roller 29 and. positively move the valve toward closed position.y

By the foregoing arrangement, we are enabled to provide aV valve'y mechanism wherein, the cam for `op..,en'ing the valve operates d1-` rectly on the valve stem without producing excessive side thrusts. This results in a simple structure and one which can be manufactured at a low cost. At the same ,time the structure is reliable in operation for the reason, among others, that the side thrusts are substantially equalized and such as do occur are taken by the supporting brackets, thus eliminating any side thrusts on the valve stem which kwould tend to make it bind.

In accordance with the provisions of the patent statutes, we have described the principle'of operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof, but we desire to have it understood that the apparatus shown is only illustrative and that 'the invention may be carriedl out by other means.

What we claim as new and desire to secure by Letters-Patent of the United States isf 1. In a valve mechanism, the combination of a valve', a stem for the valve, a cam, and a' roller carried directly by the stem which roller the cam engages to `move the valve, kthe center of the roller being located to one side ofthe center of the cam and the point of contact between: the ca-m and the roller being. between said centers;

2. InI a val-ve mechanism, the combination ofa valve, a stem for the valve, a headcounected tov the stem, a. roller carried bythe head, the center of the roller being to one sidel of the axis of the valve stem, and a cam which engages the roller to open the valve,the point of engagement of the cam with the yroller being located between the axis of the valve stem and the center of the roller, and the afxis of the cam being on the same side.. of such point o'f engagement as the axis of. the valve stem.

3. In a valve mechanism, t-he combi-nation of` a valve,` a stem for the valve, a head connected to the stem, a roller carried by the head, the center of the roller .being to one side of the axis ofthe valve stem,I a, cam which engages the roller to open the valve, the point of engagement of the cam with the lroller being located between the axis ofv the valve stemand 'the center of the roller, and the axis of the cam being on the saine side of suchI point of engagement as the axis of the valve stem, and' engaging surfaces carried by the` head and cam for transmitting side thrust from thek stem to the cam.

4. Ina valve mechanism, the combination of a.v valve, a stem for the valve, a head on t-he stem, a roller carried by the head, the center of said roller being to one side of the axis of the. valve stem, a frame structure, a: caml journaled in the frame structure and directly engaging the roller tol open the valve, the point of engagement of the cem with' the roller being located between the axis of the Valve Stem end the center of the roller, and the axis of the oem being on the l S21-Ine side of such point olf engagement as the exis of the Valve stem, e hub for the 0am, and Ineens providing on the head a, flat Snrace which rides along the eem hub and our hands this eleventh dey of February EDGAR D. DICKINSON. REGINALD G. STANDERWICK. 

